What is the function of rna polymerase? see concept 17.2 (page 342) view available hint(s) what is the function of rna polymerase? see concept 17.2 (page 342) it proceeds slowly along the dna strand, requiring about a minute to add two nucleotides to the growing mrna molecule. it relies on other enzymes to unwind the double helix. it adds nucleotides to the 5' end of the growing mrna molecule. it unwinds the double helix and adds nucleotides to a growing strand of rna. all of the abo?